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MikeD', Technician
Category: Car
Satisfied Customers: 696
Experience:  ASE Cert, AS Degree in Automotive Diagnostics
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99 dodge ram 1500 4x4 automatic 5.9 v8 has abs and brake ...

Resolved Question:

99 dodge ram 1500 4x4 automatic 5.9 v8 has abs and brake light on abs motor running with key off ignition and speedometer not working! I already replaced both rear diff and trany speed sensors. Please [email protected]
Submitted: 9 years ago.
Category: Car
Expert:  MikeD' replied 9 years ago.
You will need to take the vehicle to a repair facility for this. The fault codes must be read, a repair performed, and then the codes must be cleared. Just replacing a part, even if it is the correct part, will not repair the vehicle until the code is cleared from the module. OBD 2 codes are stored until cleared.
Customer: replied 9 years ago.
I already reset the code with a OBD 2 reader. It reset the code. The check engine light isn't coming on anymore. But the ABS light is still on and motor running. Can it be the ABS relay causing the ABS hydro motor to be working all the time? And can it be a bad relay causing the motor to stay running all the time?
Expert:  MikeD' replied 9 years ago.
It is possible, but you don't want to just shotgun the repair and start replacing parts. You need to read the ABS codes in the ABS module, Isolate the area of the problem, and test only the circuits and components related to the code stored. Note Your obd 2 reader may not be able to read codes in the ABS module. You may have to take it to the dealer or a repair facility that has the equipment to read the ABS module fault codes.
Customer: replied 9 years ago.
Understand, I replaced the speed sensors because I had a check engine light along with all the other problems, and the OBD code fault. I read somewhere that the rear diff speed sensor was usually the culprit for most abs and brake light simultaneously on, and speedometer problems. My question to you is can the abs system cause the speedometer to not work. Do I have 2 problems? And what else can cause the the speedometer not to work besides the speed sensors? I appreciate any help you can provide before I do take it to the shop this week.
Expert:  MikeD' replied 9 years ago.
Yes, Vehicle speed is calculated from an average of all speed sensors. The ABS control module receives the signal from the speed sensors and sends it to the instrument pack. If there are faults in the ABS control module, or the module is bad you will have no speedometer. If you try to read the ABS control module codes and cannot communicate with the module, you want to start by checking the fuses relating to the abs control module, and if they are good check power and ground to the ABSCM. If all checks good you may have a bad ABSCM.
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